World Journal of Orthopedics

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Moya-Angeler J et al . Current concepts on osteonecrosis of the femoral head A B Figure 2 Left hip anteriorposterior and cross leg lateral X-rays showing (arrows) the crescent sing. Figure 3 Bilateral osteonecrosis of the femoral head with flattening of the surface and early sings of osteoarthritis. Table 3 Steinberg staging system Stage Features 0 Normal radiograph, bone scan and magnetic resonance imaging Ⅰ Normal radiograph, abnormal bone scan and or magnetic resonance imaging ⅠA Mild (involves < 15% of femoral head) ⅠB Moderate (involves 15% to 30% of femoral head) ⅠC Severe (involves > 30% of femoral head) Ⅱ Cystic and sclerotic changes in the femoral head ⅡA Mild (involves < 15% of femoral head) ⅡB Moderate (involves 15% to 30% of femoral head) ⅡC Severe (involves > 30% of femoral head) Ⅲ Subchondral collapse (crescent sign) without flattening of the femoral head ⅢA Mild (involves < 15% of femoral head) ⅢB Moderate (involves 15% to 30% of femoral head) ⅢC Severe (involves > 30% of femoral head) Ⅳ Flattening of the femoral head/femoral head collapse ⅣA Mild (involves < 15% of femoral head) ⅣB Moderate (involves 15% to 30% of femoral head) ⅣC Severe (involves > 30% of femoral head) Ⅴ Joint space narrowing and/or acetabular changes ⅤA Mild ⅤB Moderate ⅤC Severe Ⅵ Advance degenerative joint disease angular measurements methods described by Kerboul and Koo and Kim and the quantitative volumetric measurement performed by quantitative digital analysis [23,24] . A recent study [25] comparing the efficacy of these systems showed more accurate and reliable measurements using the volumetric measurement method [25] . However, simpler measurement systems, though less accurate, are more commonly utilized since volumetric measurements are technically too demanding for general use. In spite of that, the size of the necrotic region must be determined as part of a comprehensive evaluation of this condition. Current ON diagnosis is dependent upon plain AP and frog-leg lateral radiographs of the hip, followed by MRI. The AP radiographs will usually demonstrate the primary area of involvement once changes can be viewed. Generally, the first radiographic changes seen by radiograph will be cystic and sclerotic changes in the FH. Subtle osteosclerotic or cystic changes in the subchondral regions may be missed because the anterior and posterior acetabular margins overlap the superior FH, therefore lateral frog-leg radiographs of the FH are necessary. Early delamination of the cartilage from the underlying bone will most likely be demonstrated by the crescent sign (Figures 2 and 3) [15] . Flattening of the FH can also be viewed by radiograph, but may only be visible in one view [15] . Although the diagnosis may be made by radiograph, plain radiographs are generally insufficient for early diagnosis; therefore MRI is considered the most accurate benchmark [5] . A single-density line on T1-weighted images and a high signal intensity line on T2-weighted images represent the early necrotic-viable bone interface and the hypervascular granulation tissue characterizing ON (Figure 4) [13] . However, recently subchondral insufficiency fractures of the FH have been proposed as a new concept regarding FH collapse with a reported incidence of 5%-10% of patients who underwent a hip replacement with a diagnosis of ONFH [26,27] . These entities must be differentiated since AVN represents an irreversible condition, which might lead to permanent joint failure and SIF may either completely resolve or progress toward epiphyseal collapse [28-30] . The characteristic finding of SIF on MRI is a low intensity band on T1 in association with bone marrow edema, however, this finding has also been described in ONFH. A recent study [30] demonstrated that the shape of the low intensity band (on T1-weighted MRI) is helpful for differentiation between the two diagnoses. The low intensity band seen in SIF is generally irregular, serpiginous, discontinuous, and convex to the articular surface, while the band in ONFH tends to be smooth, concave and well circumscribed. However, the shape of the low intensity band is not always diagnostic and further imaging may be required (MRI with gadolinium). Ultimately, both clinical and MRI characteristics need to be evaluated for the critical differentiation of both conditions (Table 4). Other functional tools for evaluating ON include measuring bone-marrow pressure, venography, and core WJO|www.wjgnet.com 593 September 18, 2015|Volume 6|Issue 8|
Moya-Angeler J et al . Current concepts on osteonecrosis of the femoral head A B C D Figure 4 Magnetic resonance imaging of the left hip showing extensive avascular necrosis of the femoral head with collapse and a large area of devitalized bone demonstrating fibrocystic change. There is associated severe arthrosis of the left hip joint with a moderate effusion, synovitis and debris and a marked bone marrow edema pattern on both sides of the joint. Table 4 Clinical and imaging differences between osteonecrosis femoral head and subchondral insufficiency fracture biopsy. While these tests are specific and sensitive, they are invasive and only used when MRI, and radiograph reveal negative findings in a patient where ON is highly likely. Although CT scans can aid in distinguishing between late stages of ON before collapse of the FH, this modality is rarely used due to its high doses of radiation. Characteristic features that define the diagnosis of ON include: collapse of the FH, anterolateral sequestrum, or the crescent sign, or when a double-line sign is demonstrated through MRI on T2-weighted images, or there is a positive histologic finding upon bone biopsy. Non-surgical management The aim of treatment of AVN of the hip is to prevent SIF ONFH Age/sex Elderly/female 30 s to 40 s Etiology Osteoporosis/obese Steroid/alcohol Bilateral Rare 50%-70% Shape of the band Iregular, disconnected Smooth High signal of the proximal Yes No Segment on gadolimium MRI From Yamamoto T. In: Yamamoto T. Subchondral Insufficiency Fractures of the Femoral Head. Clinics in Orthropedic Surgery 2012: 4: 3. SIF: Subchondral insufficiency fracture; ONFH: Osteonecrosis femoral head; MRI: Magnetic resonance imaging. collapse of the FH and may vary depending on the underlying etiology and stage of progression. Treatment options include pharmacologic agents, biophysical treatments, as well as joint-preserving and jointreplacing surgeries. Medical management of AVN has been increasingly used in early stages in attempt to delay the progression of the disease. Pharmacological management of AVN includes lipid lowering agents, anticoagulants, vasoactive substances, and bisphosphonates. Increases in both the number and size of circulating fat cells have been associated with the development of ON of the hip, therefore lipid lowering agents, such as statins, which reduce the rate of adipogenesis, are beneficial. Statins have been shown to provide protective effects for patients receiving steroids. It is still unclear whether statins have the ability to reverse steroid-induced ON once it has already occurred [31,32] . Anticoagulants such as enoxaparin act through the inhibition of platelets aggregation thereby increasing blood flow to ischemic areas of the bone. These agents are primarily beneficial in patients with underlying coagulopathy disorders, such as thrombophilia or hypofrinolysis [9,33] . Prostacyclin is a vasoactive agent that improves blood flow through its vasodilator effects in the terminal vessels. Although prostacyclin has shown significant improvement in both clinical and radiologic outcomes in early stages of AVN, long term benefits have yet to be established [34] . Bisphosphonates significantly reduce the incidence of collapse of the FH in osteonecrotic hips by reducing WJO|www.wjgnet.com 594 September 18, 2015|Volume 6|Issue 8|
Page 1 and 2: ISSN 2218-5836 (online) World Journ
Page 3 and 4: Denmark Lars C Borris, Arhus Morten
Page 5 and 6: Contents Monthly Volume 6 Number 8
Page 7 and 8: Submit a Manuscript: http://www.wjg
Page 9 and 10: Anari JB et al . Neuromuscular scol
Page 11 and 12: Gorgey AS et al . Adiposity and SCI
Page 21 and 22: Franklyn M et al . Aetiology and in
Page 35: Moya-Angeler J et al . Current conc
Page 39 and 40: Moya-Angeler J et al . Current conc
Page 47 and 48: Rabinovich RV et al . Review of com
Page 59 and 60: Paxton RJ et al . Physical activity
Page 67 and 68: Emara KM et al . Biological managem
Page 73 and 74: Sathiyakumar V et al . Isolated sac
Page 81 and 82: Kumar V et al . Total hip replaceme
Page 83 and 84: Kumar V et al . Total hip replaceme
Page 85 and 86: Zink JV et al . Quantitative MRI of
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Zink JV et al . Quantitative MRI of
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Ebraheim NA et al . Periprosthetic
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World Journal of Orthopedics

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